COI Funded Project: Rationalizing Nutrient Control in the Coastal Ocean: The Importance of Scientific Research

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January 1, 2001Project Funded: 2001

Proposed Research

A wide variety of human activities result in substantial introductions
of macronutrients into rivers, estuaries, and the coastal ocean.
These introductions enhance the potential for over-enrichment of
coastal water bodies, and, if eutrophic conditions set up, then
significant environmental and economic damages may result. At present,
the control of nutrient pollution in the United States is haphazard
and uncoordinated across media. In order to move toward a more rational
nutrient control policy, the characteristics of nutrient loading,
including its variability, must be understood more clearly. In particular,
it is critical to elucidate the roles that ocean processes play
as both a source of and a sink for nutrients.

The overall goal of the proposed project is to enhance the relevance
to society of oceanographic research on nutrient fluxes in the coastal
ocean. We propose to characterize the usefulness of scientific research
about the role of ocean processes in regulating nutrient loads.
Further, we propose to estimate the economic impacts of the development
of scientific information on nutrient fluxes in the coastal ocean.
This research is interdisciplinary, representing an important new
area of inquiry for WHOI.

Final Report

A wide variety of human activities
result in substantial introductions of macronutrients into rivers,
estuaries, and the coastal ocean. These introductions enhance
the potential for the over-enrichment (eutrophication) of coastal
water bodies. If eutrophic conditions become established,
significant environmental and economic damages may result.
In recent years, over-enrichment of coastal ecosystems by nutrients,
particularly nitrogen, has emerged as the most widespread and measurable
effect of pollution on living marine resources and biodiversity
in coastal waters.

At present, the control
of nutrient pollution in the United States is haphazard and uncoordinated
across media ( e.g. , water, atmosphere). In order
to move toward a more rational nutrient control policy, the characteristics
of nutrient loading, including its variability, must be understood
more clearly. In particular, it is critical to elucidate
the roles that ocean processes play as both a source of and a sink
for nutrients.

A burgeoning literature
on nutrient pollution and management in coastal waters demonstrate
how nutrients enter coastal waters through point sources ( e.g
., wastewater treatment plants) and non-point sources ( e.g
., runoff from agricultural lands and atmospheric depositions).
Sources of nutrients are associated with various economic
activities, such as fossil-fuel combustion (NO x ), fertilizer applications,
and waste disposal. Importantly, the ocean may play a significant
role in controlling the flow of nutrients through coastal waters,
including acting as a net supplier of nutrients to estuaries or
coastal embayments.

In this study, we develop
an analytical model of nutrient management in a coastal community.
A degree of scientific uncertainty is inevitable and is associated
with the sources of nutrients and processes regulating nutrient
cycling in coastal waters. The model may be used to estimate
the value of environmental research required to resolve the uncertainty.
We illustrate the model using a numerical simulation of a
hypothetical case.

In the model, coastal water
pollution may be the consequence of marine processes, economic activities,
or some combination of the two. Our results suggest that when nutrient
over-enrichment is the result of economic activity, then the optimal
level of activity is lower than when nutrient levels are supplied
by natural sources. The results highlight the importance
of environmental research on nutrient sources and coastal ocean
processes.

The difference between
the optimal levels of economic activity both with and without uncertainty
results in a difference in net economic benefits. This difference
is a measure of the value of environmental research. Our
simulation results show clearly that, when economic activity has
little effect on water quality and the ocean plays the key role
in regulating nutrients at a specific location, the benefits of
research could be substantial. Generally speaking, research
is more valuable if it leads to unexpected findings. If, however,
the outcome of research is more or less expected, the value of research
will be small. We find that the average value of environmental
research, which is a measure of what the community should be willing
to pay for improved understanding of nutrient cycling processes,
is on the order of 2.5 percent of the total damages from coastal
nutrient over-enrichment. This proportion may be sensitive
to the functional forms describing the scientific uncertainty.

In addition to the level
of economic activity, we extend our model to examine the optimal
levels of investment in pollution control. We show that uncertainty
about the role of the coastal ocean in regulating nutrients may
cause either under- or over-investment in controlling nutrients
from economic activities. Although we have focused our analysis
on nutrient control in coastal waters, the analytical framework
is potentially applicable to many other environmental issues ( e.g
., climate change) in which uncertainty exists with respect
to the cause of environmental degradation ( i.e ., natural
processes versus economic activities).

WHOI Geochemist Matt Charette (left) and
Research Assistant Craig Herbold measure nitrate concentration
in a Cape Cod estuary using a nitrate analyzer. They can track
groundwater-derived nutrients and identify their sources by
analyzing chemical tracer data from this instrument. (Tom Kleindinst, WHOI)

In this example, scientific uncertainty is captured by an unknown parameter r . When r = 0, nutrients in coastal waters are controlled entirely by ocean processes. By contrast, when the ocean has no effect on the nutrient cycling process, r is large (0.13). The uncertainty associated with the value of r may be resolved through research. The figure shows that the value of research is affected by its outcome (the true value of r ). If r is close to zero, the value of research is $18 million. When r is in the neighborhood is its expected value (0.06), however, the value of research is low. The average value is approximately $5 million. Generally speaking, research is more valuable if it lead to unexpected discoveries.

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